Cho–Duan–Ge decomposition Clairaut equation Einstein field equation Hamilton–Jacobi equation Hilbert space linearization Kirchhoff’s integral theorem Klein–Gordon–Fock equation Lie-Poisson action Lie–Poisson structure Maxwell’s vacuum equations Noether symmetry Poisson manifold abstracting algebra of symmetry operators arithmetic arity asymptotic conditions bic Book Industry Communication::G Reference, information & interdisciplinary subjects::GP Research & information: general bic Book Industry Communication::P Mathematics & science::PH Physics black holes canonical gravity coherent states conformable differential constraintless formalism covariance current Lie algebra representation current algebra symmetry detector clicks diffeomorphism group dirac reduction